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Nuclear Theory·nucl-th

Wednesday·August 17, 2016

7 papers—4 primary·3 cross-listed

All7Primary4Cross-lists3
  1. 01

    [Submitted on 16 Aug 2016]

    Ground State Properties of Neutron Magic Nuclei

    G. Saxena · M. Kaushik

    A systematic study of the ground state properties of the entire chains of even even neutron magic nuclei represented by isotones of traditional neutron magic numbers N = 8, 20, 40, 50, 82 and 126 has been carried out using relativistic mean field (rmf) plus Bardeen Cooper Schrieffer (BCS) approach. Our present investigation includes deformation, binding energy, two proton separation energy, single particle energy, rms radii along with proton and neutron density profiles, etc. Several of these results are compared with the results calculated using non relativistic approach (Skyrme Hartree Fock method) along with available experimental data and indeed they are found with excellent agreement. In addition, the possible locations of the proton and neutron drip lines, the (Z,N) values for the new shell closures, disappearance of traditional shell closures as suggested by the detailed analyzes of results are also discussed in detail.

    Comments:
    26 pages, 11 figures, Accepted in Physics of Atomic Nuclei, 2016
    Subjects:
    Nuclear Theory (nucl-th)
    arXiv:
    1608.04505 [pdf]
    Phys.Atom.Nucl.(2017)·7 citations
  2. 02

    [Submitted on 15 Aug 2016]

    Consequences of simultaneous chiral symmetry breaking and deconfinement for the isospin symmetric phase diagram

    Tobias Fischer🇵🇱 · Thomas Klähn🇵🇱 · Matthias Hempel🇨🇭

    The thermodynamic bag model (tdBag) has been applied widely to model quark matter properties in both heavy-ion and astrophysics communities. Several fundamental physics aspects are missing in tdBag, e.g., dynamical chiral symmetry breaking (DSB) and repulsions due to the vector interaction are both included explicitly in the novel vBag quark matter model of Klähn and Fischer (2015) (Astrophys. J. 810, 134 (2015)). An important feature of vBag is the simultaneous DSB and deconfinement, where the latter links vBag to a given hadronic model for the construction of the phase transition. In this article we discuss the extension to finite temperatures and the resulting phase diagram for the isospin symmetric medium.

    Comments:
    6 pages, 2 figures, Contribution to the Topical Issue Exploring strongly interacting matter at high densities - NICA White Paper edited by David Blaschke et al
    Subjects:
    Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph)
    arXiv:
    1608.04613 [pdf]
    EPJA(2016)·6 citations
  3. 03

    [Submitted on 16 Aug 2016]

    Corrections to nucleon capture cross sections computed in truncated Hilbert spaces

    B. Acharya · A. Ekström · D. Odell · T. Papenbrock · L. Platter

    Nucleon capture cross sections enter various astrophysical processes. The measurement of proton capture on nuclei at astrophysically relevant low energies is a challenge, and theoretical computations in this long-wavelength regime are sensitive to the long-distance asymptotics of the wave functions. A theoretical foundation for estimating and correcting errors introduced in capture cross sections due to Hilbert space truncation has so far been lacking. We derive extrapolation formulas that relate the infrared regularized capture amplitudes to the infinite basis limit and demonstrate their efficacy for proton-proton fusion. Our results are thus relevant to current calculations of few-body capture reactions such as proton-proton fusion or proton capture on the deuteron, and they also open the way for the use of {\it ab initio} many-body wave functions represented in finite Hilbert spaces in precision calculations of nucleon capture on heavier nuclei.

    Comments:
    6 pages, 4 figures, published version
    Subjects:
    Nuclear Theory (nucl-th)
    arXiv:
    1608.04699 [pdf]
    PRC(2017)·8 citations
  4. 04

    [Submitted on 16 Aug 2016]

    Thermal Effects in Dense Matter Beyond Mean Field Theory

    Constantinos Constantinou · Sudhanva Lalit · Madappa Prakash

    The formalism of next-to-leading order Fermi Liquid Theory is employed to calculate the thermal properties of symmetric nuclear and pure neutron matter in a relativistic many-body theory beyond the mean field level which includes two-loop effects. For all thermal variables, the semi-analytical next-to-leading order corrections reproduce results of the exact numerical calculations for entropies per baryon up to 2. This corresponds to excellent agreement down to sub-nuclear densities for temperatures up to MeV. In addition to providing physical insights, a rapid evaluation of the equation of state in the homogeneous phase of hot and dense matter is achieved through the use of the zero-temperature Landau effective mass function and its derivatives.

    Comments:
    24 pages, 11 figures, Contribution to Gerry Brown's 90th Birthday Memorial Book
    Subjects:
    Nuclear Theory (nucl-th)
    arXiv:
    1608.04713 [pdf]
    IJMPE(2017)·8 citations
  5. 05

    [Submitted on 15 Aug 2016] (cross-list from nucl-ex)

    Ordering of the and proton levels in light nuclei

    C. R. Hoffman · B. P. Kay · J. P. Schiffer

    A survey of the available single-proton data in nuclei, along with calculations using a Woods-Saxon potential, show that the ordering of the and proton orbitals are determined primarily by the proximity of the -state proton energy to the Coulomb barrier. This is analogous to the dependence of the corresponding neutron orbitals in proximity to the neutron threshold, that was previously discussed.

    Subjects:
    Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
    arXiv:
    1608.04427 [pdf]
    PRC(2016)·17 citations
  6. 06

    [Submitted on 16 Aug 2016] (cross-list from hep-ph)

    Applicability of the Wigner functional approach to evolution of quantum fields

    Andrey Leonidov🇷🇺 · Anna Radovskaya🇷🇺

    Evolution of highly excited quantum field is considered in the framework of Keldysh formalism . It is demonstrated that leading order (LO) term of semiclassical approximation appears as well-known Classical Statistical Approximation (CSA). In simple case of spatially homogeneous scalar field analytical expressions for leading and next-to-leading (NLO) order are presented. It is shown that the range of applicability of CSA strongly depends on the properties of the initial state of the system

    Comments:
    Based on talk given at the 19th Intenational Seminar QUARKS 2016
    Subjects:
    High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
    arXiv:
    1608.04580 [pdf]
    EPJ Web Conf.(2016)·6 citations
  7. 07

    [Submitted on 16 Aug 2016] (cross-list from astro-ph.CO)

    Stellar Helium Burning in Other Universes: A solution to the triple alpha fine-tuning problem

    Fred C. Adams · Evan Grohs

    Motivated by the possible existence of other universes, with different values for the fundamental constants, this paper considers stellar models in universes where Be is stable. Many previous authors have noted that stars in our universe would have difficulty producing carbon and other heavy elements in the absence of the well-known C resonance at 7.6 MeV. This resonance is necessary because Be is unstable in our universe, so that carbon must be produced via the triple alpha reaction to achieve the requisite abundance. Although a moderate change in the energy of the resonance (200 -- 300 keV) will indeed affect carbon production, an even smaller change in the binding energy of beryllium ( keV) would allow Be to be stable. A stable isotope with would obviate the need for the triple alpha process in general, and the C resonance in particular, for carbon production. This paper explores the possibility that Be can be stable in other universes. Simple nuclear considerations indicate that bound states can be realized, with binding energy MeV, if the fundamental constants vary by a percent. In such cases, Be can be synthesized through helium burning, and C can be produced later through nuclear burning of beryllium. This paper focuses on stellar models that burn helium into beryllium; once the universe in question has a supply of stable beryllium, carbon production can take place during subsequent evolution in the same star or in later stellar generations. Using both a semi-analytic stellar structure model as well as a state-of-the-art stellar evolution code, we find that viable stellar configurations that produce beryllium exist over a wide range of parameter space. Finally, we demonstrate that carbon can be produced during later evolutionary stages.

    Comments:
    48 pages, 9 figures, accepted to Astroparticle Physics
    Subjects:
    Cosmology and Nongalactic Astrophysics (astro-ph.CO); Solar and Stellar Astrophysics (astro-ph.SR); Nuclear Theory (nucl-th)
    arXiv:
    1608.04690 [pdf]
    Astropart.Phys.(2017)·8 citations

Affiliations

first authorsco-authorsvia INSPIRE